1. Field of the Invention
The disclosure relates to a liquid crystal display device, and more particularly, to a liquid crystal display device including a patterned retarder layer.
2. Discussion of the Related Art
Recently, with the rapid development of information technologies, various display devices for displaying images have been proposed. Liquid crystal display devices, which are able to display not only two-dimensional images but also three-dimensional images, have been developed.
Human beings perceive depth and a three-dimensional effect due to psychological and memorial factors in addition to a binocular disparity from a separation distance of eyes.
As one of the methods for displaying three-dimensional images using these factors, a stereoscopic type uses a physiological factor of both eyes to perceive the three-dimensional effect.
The stereoscopic type uses stereography in which, when two-dimensional linking images including parallax information are provided to left- and right-eyes spaced apart from each other with a distance of about 65 mm, the brain produces space information about the front and the rear of the screen during merging them and thus perceives the three-dimensional effect.
The stereoscopic type may be classified into a glasses type, where the user wears specific glasses, and a glasses-free type, where a parallax barrier or a lens array such as lenticular or integral is used at a display side, depending on a position in which a substantial three-dimensional effect is produced.
The glasses type has wider viewing angles and causes less dizziness than the glasses-free type. In addition, the glasses type can be manufactured with relatively low costs.
The glasses type may be classified into a shutter glasses-type and a polarization glasses-type.
In the shutter glasses-type, left- and right-eye images are alternately displayed in a screen, sequential opening and closing timing of a left shutter and a right-shutter of the shutter glasses is accorded with alternation time of the left- and right-eye images, and the respective images are separately perceived by the left eye and the right eye, thereby producing the three-dimensional effect.
In the shutter glasses-type, the alternation timing of the images may not be controlled to be completely accorded. Thus, flicker may occur, and this may cause fatigue such as dizziness while watching the images.
In the polarization glasses-type, pixels of a screen are divided into two parts by columns, rows or pixels, left- and right-eye images are displayed in different polarization directions, the left-glass and the right-glass of the polarization glasses have different polarization directions, and the respective images are separately perceived by the left eye and the right eye, thereby producing the three-dimensional effect.
The polarization glasses-type does not have factors of causing flicker, and fatigue is less caused while watching the images.
In addition, since the polarization glasses-type can use a polarization dividing optical means, which is patterned and is able to divide polarized light, such as a patterned retarder, for example, on a front surface of a display panel, the viewer can wear polarization glasses, which are very cheaper than the shutter glasses, to watch it. Accordingly, costs of the polarization glasses-type are relatively low.
Hereinafter, a polarization glasses-type liquid crystal display (LCD) device of the related art will be described with reference to accompanying drawings.
FIG. 1 is a cross-sectional view of schematically illustrating a polarization glasses-type LCD device according to the related art and explains a three dimensional (3D) crosstalk, FIG. 2 is a cross-sectional view of schematically illustrating a polarization glasses-type LCD device including a black stripe to remove a 3D crosstalk according to the related art.
In FIG. 1, the polarization glasses-type LCD device 1 according to the related art includes a first substrate 10, a second substrate 20 and a third substrate 50. Gate lines (not shown), data lines (not shown) and thin film transistors (not shown) are formed on the first substrate. The second substrate 20 includes left-eye horizontal pixel lines HI, right-eye horizontal pixel lines Hr and black matrix BM. A patterned retarder 52 is formed on the third substrate 50 by applying reactive mesogen.
A liquid crystal panel 30 is formed by attaching the first substrate 10 and the second substrate 20 and produces images.
A first polarizer (not shown) is attached at a lower surface of the first substrate 10, and a second polarizer 40 is attached at an upper surface of the second substrate 20.
Here, the first polarizer (not shown) and the second polarizer 40 transmit linearly polarized light, which is parallel to respective transmission axes. The transmission axis of the first polarizer (not shown) is perpendicular to the transmission axis of the second polarizer 40.
The patterned retarder 52 is attached at an upper surface of second polarizer 40. The patterned retarder 52 includes left-eye retarders RI and right-eye retarders Rr.
At up and down viewing angles of the polarization glasses-type LCD device, as shown in a portion A, some of the left-eye image II′ displayed by the left-eye horizontal pixel lines HI passes through the right-eye retarder Rr of the patterned retarder 52 and is right-circularly polarized differently from front or left and right viewing angles.
Then, the some of the left-eye image II′ circularly polarized passes through the right-eye lens of the polarization glasses 70 together with the right-eye image Ir circularly polarized and is transmitted to the right-eye of the viewer.
Therefore, 3D crosstalk occurs due to the interference between the right-eye image Ir and the some of the left-eye image II′, and the up and down viewing angles in the 3D mode are decreased.
Here, the 3D crosstalk means that recognition of the clear 3D image is disturbed by providing the left-eye image II to the right-eye or providing the right-eye image Ir to the left-eye. The resolution of the 3D image increases and tiredness of the eyes decreases as the 3D crosstalk gets small.
To prevent occurrence of the 3D crosstalk, as shown in FIG. 2, the polarization glasses-type liquid crystal display device 11 of the related art includes a black stripe BS over the patterned retarder 52. The black stripe BS is disposed between the left-eye retarder RI and the right-eye retarder Rr.
The some of the left-eye image II′, which passes through the left-eye horizontal pixel line HI of the liquid crystal panel 30 and goes into the right-eye retarder Rr of the patterned retarder, is blocked by the black stripe BS.
As a result, only the right-eye image Ir is circularly polarized and is transmitted to the right-eye of the viewer through the right-eye lens of the polarization glasses 70. The 3D crosstalk due to the interference between the right-eye image Ir and the some of the left-eye image II′ is prevented.
However, the non-display area of the liquid crystal panel 30 is increased due to the black stripe BS. The aperture ratio and the brightness are decreased.
In addition, the polarization glasses-type liquid crystal display device 1 or 11 uses a glass substrate for the third substrate 50 on which the patterned retarder 52 is formed.
The glass substrate has advantages of superior surface flatness, high transparency, and uniform optical properties without birefringence. Moreover, an alignment layer or reactive mesogens can be formed on the glass substrate with a uniform thickness by a spin coating method.
On the other hand, the glass substrate is expensive, is fragile during processes and causes low yields and productivity due to long manufacturing time.